1. Technical Field
The present invention relates to liquid crystal displays (LCDs) and manufacturing methods for the LCDs and, more particularly, to an LCD with alignment films and a manufacturing method for the LCD.
2. Description of the Related Art
Because LCDs have the advantages of portability, low power consumption, and low radiation, they have been widely used in various portable information products such as notebooks, personal digital assistants (PDAs), video cameras, and the like. Furthermore, LCDs are considered to have the potential to completely replace cathode ray tube (CRT) monitors and televisions.
Referring to FIG. 4, a conventional LCD 100 generally includes a first base plate 102, a second base plate 110, and a liquid crystal layer 118 located between the two base plates 102 and 110. An alignment layer 106 is formed on an inner surface 104 of the first base plate 102. An alignment layer 114 is formed on an inner surface 112 of the second base plate 110.
The liquid crystal layer 118 includes a plurality of rod-like liquid crystal molecules 120. A plurality of parallel fine grooves 108 is formed on an inner surface of the alignment layer 106. A plurality of parallel fine grooves 116 is formed on an inner surface of the alignment layer 114. Functions of the grooves 108 and 116 are to orient the liquid crystal molecules 120 in a homogeneous manner, i.e., to align the liquid crystal molecules 120 adjacent to the alignment layers 106 and 114 parallel to the grooves 108 and 116 respectively. When the grooves 108 and 116 are at right angles, the liquid crystal molecules 120 can automatically turn 90 degrees from top to bottom.
The alignment layers 106 and 114 are important to the LCD 100. Alignment qualities of the alignment layers 106 and 114 are one of the key factors that determine the display quality of the LCD 100. The alignment layers 106 and 114 can be made using a rubbing method. The rubbing method can be exemplified using the manufacturing method for the alignment layer 114 as below. The manufacturing method for the alignment layers 114 generally includes the steps of: coating a layer of alignment material, such as polyimide, on the inner surface 112 of the second base plate 110; and rubbing the surface of the alignment material using rubbing cloth to form the plurality of fine grooves 116.
However, some drawbacks arise from a mechanical contact of the rubbing cloth with the surface of the alignment material. This method is complicated because a baking process of the polyimide layer takes long time, and the rubbing introduces numerous electrostatic charges as well as plenty of dust contamination, which in turn needs other facilities and rinse process to eliminate. In addition, the rubbing cloth has a limited lifespan and needs to be replaced frequently.
What is needed, therefore, is an LCD with a good alignment quality and a simple manufacturing method therefor.